As stated in earlier issued U.S. Pat. No. 4,562,987, the relatively frequent use of computer terminals in offices has significantly changed the physical requirements of office workplaces. Whether the computer terminal is a standalone unit having its own processor or a remote terminal of a central computer system, it generally consists of an input device such as, for example, a keyboard and/or a numeric keypad, and an output device such as, for example, a cathode ray tube (CRT), a liquid crystal display or some other numeric, alpha-numeric or graphic display device. The input device and the display device may be physically separate using, for example, a flexible cord to permit independent movement of the input device for accommodating the individual needs of the worker, or the input device and the display device may be integrated into a single unitary assembly.
A worker at a computer terminal may be required to spend long hours in a more constrained physical posture than is required of workers at various other business tasks. In order to maintain worker comfort and efficiency, more attention must be given to requirements related to the posture and other physical needs of workers stationed at computer terminals. These include appropriate desk height and design, chair design for maintenance of comfortable and efficient posture and an appropriate balance between general lighting and task lighting. It is especially important to position the CRT in height, transverse position, depth position, and vertical axis rotation for comfortable viewing without excessive head and eye motion and without distracting reflections.
A computer terminal represents a substantial capital investment. Many work situations require that several workers have access to a computer terminal but do not warrant the expense of a separate computer terminal for each worker. One solution is disclosed in U.S. Pat. No. 4,305,563 wherein a computer terminal support includes means for permitting rotation about a single vertical axis and for permitting translation of the computer terminal toward and away from the vertical axis. When several workers' desks are arranged together about a single vertical axis, the display of the computer terminal may be rotated about the single vertical axis to face a worker at any one of the grouped desks and may be displaceable toward and away from the worker. Having only a single axis, this device permits very limited positioning of the display device and thus may fail to satisfy all of the requirements of the workers.
U.S. Pat. No. 4,365,561 discloses a pedestal-mounted device for supporting a computer terminal. This device provides rotation of the display device about the vertical axis of the pedestal and about a horizontal axis for angularly positioning the display device and provides vertical motion of the pedestal for vertically positioning the display device and keyboard. This device has very limited provision for horizontally positioning the computer terminal for use by even one worker since its horizontal position is rigidly constrained by the position of the pedestal. Basically, this device requires that the worker move from the normal desk location to an auxiliary work station comprised of the disclosed pedestal-mounted device with its supported computer terminal. For tasks requiring back-and-forth reference to materials at the normal desk location and at the terminal, a substantial amount of chair swivelling or sliding and worker motion is required. If use of the terminal by more than one worker is required, the workers' desks must be arranged with a substantial open space between them so that any one of them requiring access to the computer terminal can rotate the computer terminal about the vertical axis of the pedestal and then either move the regular desk chair up to the computer terminal or use a separate chair maintained at the computer terminal.
U.S. Pat. No. 4,562,987 discloses an arrangement with four pivot posts each having pivoting collars thereon with swivel arms affixed thereto. A terminal support tray is affixed to one of the swivel arms and one of the collars is vertically adjustable on its post. Other features are provided and will yield a total of five degrees of freedom of adjustment.
Other support devices are disclosed in U.S. Pat. No. 2,849,534 for supporting a tray in a drive-in restaurant; U.S. Pat. No. 2,991,138 for supporting a tray; U.S. Pat. No. 3,157,379 for supporting furniture on a wall bracket and U.S. Pat. No. 4,085,961 for supporting a tool box on a pickup truck. None of these additional references addresses or solves the problem of supporting computer terminals for efficient and comfortable use by one or more workers.
In addition to the above and relative to the invention which is to be described in detail hereinbelow, note must also be taken of U.S. Pat. Nos. 3,358,957; 3,832,789; 4,447,031; 4,516,751; 4,545,555; and 4,549,710.
In U.S. Pat. No. 3,358,957, T. L. Lindenmuth discloses a bedstead television support wherein a load is supported between the arms of a bracket which, in turn, is supported on a telescopic lever arm which, in turn, is pivotally supported on a clamp which may be affixed to the frame of a bedstead. This patent fails to reveal the utilization of parallel arrangements exerting forces which are algebraically added to the weight of a load as in the present invention and as will be shown in detail hereinbelow.
N. C. Bartram shows in U.S. Pat. No. 3,832,789 a nestible portable hair dryer involving the use of a counter-balancing feature involving the use of a wound coil spring assembly in which the coiled spring is arranged to permit the free end of a post which is fixed to a dryer element to be pulled to various positions to provide a constant tension to keep a dryer hood in any position selected by a user. The tensioning feature employed in this patent provides substantially constant tension and permits noiseless adjustment of a head between extreme elevated position and a normal elevated operating position. However, the algebraic summing of two forces provided by separate neutralizing elements as in the present invention is not shown.
In U.S. Pat. No. 4,447,031, James Souder reveals a support arm for selectively positioning heavy objects such as television sets. An arrangement is provided which consists of articulated forward and rear arms, each having parallelogram linkages which are each provided with springs to counterbalance a load weight. An adjustable friction brake arrangement is incorporated in a pivotal point of each linkage which applies a braking force to insure stable positioning of each of the arms in any position throughout the motion of the arm system notwithstanding unbalanced conditions. The arrangement herein also fails to reveal a parallel arrangement of counter-balancing forces wherein the algebraic summing of the load and counterbalancing forces is effected as in the present invention.
Charles Westbrook shows in U.S. Pat. No. 4,516,751 a vertically-adjustable bracket for supporting equipment such as video display devices. The disclosed arrangement shows a mechanism for orienting the video display devices at a desired angle and inclination, but the mechanism includes a support plate having a spherical bearing surface which is received in a circular aperture in a bracket arm. The mounting plate is held in place by a threaded shaft which is secured to a slot formed in a spherical bearing surface by a nut. This is unlike the total arrangement shown in the disclosure below as will become readily apparent.
In U.S. Pat. No. 4,545,555, there is illustrated an adjustable arm which includes a base member with a base rotatable joint member connected thereto. While this arrangement shares with the present invention various features such as the utilization of a lever arm connected to a circular pivot arrangement, the instant invention distinguishes therefrom in employing parallel arrangements which are offset against one another and which are algebraically added to the weight of a load.
Dennis Prince et al. reveals in U.S. Pat. No. 4,549,710 a supporting assembly which includes a base member having a spherical depression and a supporting platform having a hemispherical projection. While this shares features of hemispherical elements arranged in nesting relationship, this patent fails completely to reveal the algebraic summation of forces provided by parallel counterbalancing elements as will be described hereinbelow.